Integration of new network topologies into a cellular network gains more and more attraction both in industry and academy of cellular radio telecommunications. Recent developments encompass direct communication between terminal devices operating in a cellular network when the terminal devices are close to each other. An object in such direct device-to-device communication is to use valuable radio resources in the most efficient manner. As an application example of device-to-device (D2D) communication, the terminal devices may communicate directly with each other under the control of the cellular network by sharing the radio resources with cellular users, i.e. the terminal devices communicating data through the cellular network.
Terminal devices about to establish a D2D connection may be served by different operators and, thus, different radio access networks and even different radio access technologies. The terminal devices may also have individual end-to-end services (e.g. web browsing) at the same time as the common D2D connection service. Furthermore, the radio access networks of individual terminal devices may set quality-of-service parameters differently for respective radio bearers and, thus, may control the same service differently, which may result in unreliable performance of the D2D connection.